Neurochrome HP-1

I am curious as to what Tom thinks about this but the link is broken.

 

I'm not a good enough photographer to be an audio reviewer these days...

 

At some point they probably have more gear in photog than audio.

I know shigzeo (ohm-image) is now using a fuji medium format with a Hasselblad digital back for his shoots, which is pretty insane.

 

Let the nerd-fest begin. I haven't had time to line-level match between amps yet, but I'm thoroughly impressed with the HP-1 so far. More to follow.

 

I'd love to have my Hasselblad 500C/M back with a digital back for it. Of the cameras I've owned, that's the only one I actually miss. Using a Hasselblad for product shoots makes perfect sense - at least if you do it professionally.

Looking forward to hearing the impressions of the HP-1. It's good to hear it's arrived safely at the next location.

Tom

 

I can appreciate a wide variety of sonic presentations. I’m not chasing unicorns or absolutes. When it comes to hi-fi, I’m not overly opinionated and lean towards being wishy washy and passive. “Hey, I like this”, or “This is really nice”. I also haven’t had much interest in building or ‘upgrading’ audio gears recently and I’m just happy to find the time to listen to music these days. With that being said, I’ve known of Tom’s work and contributions over at diyaudio.com for some time, but have never had the opportunity to listen to any of designs and didn’t want to pass on this opportunity.

Since no component exists in a vacuum, my gears:
-Linux low-latency kernel desktop running either Audacious or Tidal
-Gungnir DS/Doodlebug
-HD600, K701, K7XX (all modified) and a HE560 (I believe these were tweaked by Bill-p for Tode?)

The HP-1 is dynamic and hits hard. I’ve not heard an amplifier this dynamic and musically engaging before. I think my former Naim gears come close. Subtle dynamic shadings that give clues to real musicians playing in real time and off one another are easily heard. It grips, hits, and grooves hard. It doesn’t do wishy washy or passive. It has complete control over the transducers. It doesn’t f**k around.

Note attack, sustain, and decay may sound a little too compact/truncated for some. While I think the HP-1 has great timbre and tone, I’m guessing some members here might prefer a fatter, rounded tone. Personally, I can hear the fundamental notes easier and musicians sound like they are playing ‘more in tune’, adding a slight tonal sweetness. I wouldn't call this a lean amplifier by any means.

I don’t really geek out on soundstaging or imaging, especially with headphones. Using the higher gain setting will push vocals and instruments a little more forward though. I also felt the higher gain setting gave better instrument separation.

I preferred the highest gain setting when running from the Gungnir unbalanced and balanced. The lowest gain setting could sound strident on some recordings with unbalanced, but notably less dynamic and coherent with both unbalanced and balanced inputs. As much as I place an emphasis on line-level matching, doing this to compare sonic differences in gain settings without an identical amp for direct A/B comparison is a fruitless endeavor. I did have enough granularity on the pot without channel imbalance either way with my headphones.

In short, I’m hard pressed to think of a more resolving and enjoyable solid state amplifier I’ve had the pleasure of listening to. It has a small form factor for a desktop, accepts balanced and unbalanced inputs, it’s dead quiet, and has measured power with a potent, musically engaging presentation that should spank any headphone with ease. I’ve not been this excited about a hi-fi gear in a long time. I can’t wait to build one for myself. In case none of what I wrote above make any sense, a picture(s) is worth a thousand words.

The HP-1 is like...





The HP-1 makes me feel like...

 

I found myself preferring the low-gain setting myself, though as you said without an identical amp such comparisons are very very difficult.

Of notable difference on my end, I always left the HP-1 pot at max and controlled volume through my pre/mixer/dac/etc.

 

@fishski13: Thank you for your synopsis. I appreciate it. It's always good to hear the listening impressions.

Yeah... For the clearest picture, you have to level match which makes a quick A/B comparison difficult. If your DAC has a volume control with readout in dB you could compensate there, though who knows if that changes the tone or performance of the DAC (I suspect not much, but that is an unknown).

Either way, we don't all have to like the same settings. As long as you can find a setting that you do like, life is grand.

That's how I use it as well.

Tom

 

I forgot to mention and clarify that running balanced input with a Gungnir that puts out 4.0Vrms caused clipping on some of my recordings - quieter mastered classical and ECM label stuff weren't an issue, but I had to twiddle with the volume control in Tidal if I wanted to rock out to Aimee Mann or Katy Perry. I listened mostly to unbalanced at high gain and balanced at medium gain, with most listening done with unbalanced inputs. Honestly, after more listening tonight, I can't hear any difference between medium and high gain. I'm not going to bother fiddling about with discerning differences between the gain settings anymore. I'm bummed to see this amp leave chez fish.

 

±18 V rails, 4.0 V RMS (= 5.66 V peak) gain of 10x (20 dB) -> 56 V. Yeah. That should result in clipping.

The gain stage is before the volume control to avoid amplifying the noise of the volume pot, so if you're running 4.0 V RMS in and have the gain set to the highest setting, the input stage will clip.

Tom

 

Wow, so the Hp-1 has something in common with the O2.

 

Maybe NwAvGuy was a competent designer after all...

Tom

 

You don't think clipping with pretty standard input voltages is bad design??

 

You think clipping at the 20 dB gain setting on a balanced input with two lower gain settings available, including a pretty standard 4X (12 dB) setting, is bad design???

 

You're right. Noise performance vs gain structure is a tradeoff.

The HP-1 does *not* clip on any standard voltage on the low (+6 dB) and medium (+12 dB) gain settings. The high (+20 dB) gain setting is intended for use with 0.9 V RMS sources (many small DACs, tablets, phones, whatnot).

Sure, I can move the gain after the volume control. That would result in 6, 12, or 20 dB worse SNR depending on the gain setting chosen. Attenuate -> Amplify is universally bad for noise performance. To me, Attenuate -> Amplify is a very bad design practice.

I optimized for noise performance as I really dislike the persistent hisssssssss..... that you hear in many amps. I want my headphone amp to be dead quiet. To me, that's good design and good engineering. This means the gain stage has to be before the volume control. The implication of that is that if you apply a 4.0 V signal when using the high gain setting, the input stage will clip. Tradeoffs, tradeoffs. There is a very easy solution to this: Use the low or medium gain setting.

Tom

 

The infamous NwAvGuy provided some rough guidelines on useful gain settings for source vs load in this table:

Code:

Headphones                                            Portable   USB DAC   HOME <- Source
IEM 100 - 115 dB/mW 16 - 32 ohms                      1X/0 dB    1X/0 dB   1X/0 dB    
Sensitive Low Impedance Full Size Grado, Denon, Etc.  2X/6 dB    1X/0 dB   1X/0 dB    
Average Full Size HD5xx/600/650 100 - 300 ohm         5X/14 dB   3X/10 dB  2X/6 dB    
High Impedance Full size 300 - 600 ohm                10X/20 dB  5X/14 dB  3X/10 dB